Optical readers tend to fall into one of three categories: wand readers, laser scan engine optical readers and image sensor based optical readers.
Wand readers generally comprise a single light source and single photodetector housed in a pen shaped housing. A user drags the wand reader across a decodable symbol (e.g., a bar code) and a signal is generated representative of the bar space pattern of the bar code.
Laser scan engine based optical readers comprise a laser diode assembly generating a laser light beam, a moving mirror for sweeping the laser light beam across a decodable symbol and a signal is generated corresponding to the decodable symbol.
Image sensor based optical readers comprise multi element image sensors such as CID, CMOS, or CCD image sensors and an imaging optic for focusing an image onto the image sensor. In operation of an image sensor based optical reader, an image of a decodable symbol is focused on an image sensor and a signal is generated corresponding to the signal. Image sensor elements may be arrayed in a line or in a rectangular matrix or area. Area image sensors capture a digital picture and use software algorithms to find and decode one or more symbols.
Users of laser scanner engine based optical readers have been switching in increasing numbers to image sensor based optical readers. Image sensor based optical readers are more durable and offer additional features relative to laser scan engine based bar code readers. Features and functions which have been incorporated into image sensor based optical readers involve image processing.
An image sensor based optical reader having image processing functionality is described in U.S. Pat. No. 6,298,176, issued Oct. 2, 2001, entitled “Symbol-Controlled Image Data Reading System,” assigned to the assignee of the present invention and incorporated by reference. In the patent, an optical reader is described which reads an image data reading instruction symbol and which outputs image data which may include signature data in manner that depends on the information encoded in the image reading instruction symbol.
The added functionality possible with optical readers, coupled with reduced costs, has made optical readers attractive to an ever-widening market of users who seek to employ optical readers in an ever-growing variety of applications. Manufacturers of optical readers have been tested in satisfying all of their customer demands for readers, which can satisfy a greater variety of optical reader applications. Accordingly, there is a need for an optical reader which can readily be custom programmed to operate in a manner consistent with a user's particular application.